This post introduces PostgreSQL and walks you through the installation and configuration of version 9.3 on Linux®.
Introduction
PostgreSQL is the world’s most advanced open-source Relational Database Management System (RDBMS). Many leading organizations, such as Apple, IMDB, Skype, Uber, Lockheed Martin, Verizon, and others, use PostgreSQL. This RDBMS began in 1986 as part of the POSTGRES project at the University of California at Berkeley and has more than 30 years of active development on the core platform.
PostgreSQL runs on all major operating systems and has been ACID-compliant since 2001. The acronym ACID consists of the following components:
- Atomicity: You guarantee that either the entire transaction succeeds or none of it does.
- Consistency: You guarantee that all data is consistent. All data is valid according to the defined rules. The rules include constraints, cascades, and triggers applied to the database.
- Isolation: All transactions occur in isolation. The transaction cannot read data from any other transaction that has not yet completed.
- Durability: After you commit a transaction, it remains in the system, even if there’s a system crash immediately following the operation.
Unsurprisingly, PostgreSQL serves as the open-source relational database of choice for many people and organizations because of its powerful add-ons such as the popular PostGIS geospatial database extender.
Image Source: https://postgresql-database.blogspot.com/2013/08/postgresql-architecture.html
Support
Production support SLA’s available from the following companies:
- https://www.enterprisedb.com
- https://www.2ndquadrant.com/
- https://www.revsys.com/
- https://imperoit.com/PostgreSQL_Support.htm
Supported Versions: Current (12) / 11 / 10 / 9.6 / 9.5 / 9.4 Development Versions: devel Unsupported versions: 9.3 / 9.2 / 9.1 / 9.0 / 8.4 / 8.3 / 8.2
Installation and Configuration
Perform the following steps to install and configure Postgres 9.3:
Install Postgres 9.3 on Linux 7.1
Run the following command to install Postgres 9.3 on Red Hat® Linux 7.1:
[root@snwdbsolpeprod01 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.1 (Maipo)
Create an empty folder
Create an empty folder for the database installation.
[root@snwdbsolpeprod01 mnt]# mkdir postt
[root@snwdbsolpeprod01 postt]# pwd
/mnt/postt
Download the RPM
Run the following command to download the Red Hat Package Manager (RPM) for your OS version to start the Postgres installation:
[root@snwdbsolpeprod01 postt]# wget https://yum.postgresql.org/9.3/redhat/rhel-7-x86_64/pgdg-redhat93-9.3-2.noarch.rpm
Install the RPM
Install the RPM package by using the following command:
root@snwdbsolpeprod01 postt]# rpm -ivh pgdg-redhat93-9.3-2.noarch.rpm
Install additional packages
After you install RPM, you need to install some Postgre packages that install the DB software.
[root@snwdbsolpeprod01 postt]# yum install postgresql-contrib.x86_64
[root@snwdbsolpeprod01 postt]# yum install postgresql93-server.x86_64
Configure the PGDATA location
Determine where to store the data. To use a non-default location for data, edit the PostgreSQL service sysconfig file, and change the PGDATA argument.
vi /etc/rc.d/init.d/postgresql
vi /etc/sysconfig/pgsql/postgresql
NOTE: If PostgreSQL in sysconfig/pgsql does not exist, create it and add a line denoting where you want to store the data, as shown in the following example:
[root@snwdbsolpeprod01 pgsql]# cd /etc/sysconfig/pgsql/
[root@snwdbsolpeprod01 pgsql]# vi postgresql
[root@snwdbsolpeprod01 pgsql]# cat postgresql
PDGATA=/mnt/postt
Initialize the database
The first command (only needed once) is to initialize the database in PGDATA.
service <name> initdb
For example: for version 9.3:
service postgresql-9.3 initdb
or
/usr/pgsql-9.3/bin/postgresql93-setup initdb
[root@snwdbsolpeprod01 data]# /usr/pgsql-9.3/bin/postgresql93-setup initdb
Initializing database ... OK
Set Postgres to start automatically
If you want PostgreSQL to start automatically when the OS starts, use the following command:
[root@snwdbsolpeprod01 data]# chkconfig postgresql-9.3 on
Note: Forwarding request to ‘systemctl enable postgresql-9.3.service’.
Start the PostgreSQL service
To start the PostgreSQL service, run the following command:
[root@snwdbsolpeprod01 data]# systemctl start postgresql-9.3.service
Configure the database
You can easily configure the database by updating postgresql.conf as shown in the following example:
vi /var/lib/pgsql/9.3/data/postgresql.conf
Change the following:
listen_address = ‘*’
port = 15000
max_connections=300
shared_buffers = 8192MB # min 128kB
# (change requires restart)
temp_buffers = 128MB # min 800kB
max_prepared_transactions = 20 # zero disables the feature
log_destination = 'csvlog'
logging_collector = on
log_directory = '/mnt/pgsql/logs'
log_filename = 'postgresql-%a.log'
#------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------
autovacuum = on
# Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
autovacuum_naptime = 10080min # time between autovacuum runs
autovacuum_vacuum_threshold = 1000 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum Multixact age
# before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
Configure database connection settings
To restrict or manage the database connection setting, run the following command:
vi /var/lib/pgsql/9.3/data/pg_hba.conf
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all peer
local all postgres md5
local all postgres ident
# IPv4 local connections:
# IPv6 local connections:
host all all ::1/128 ident
host all all 0.0.0.0/0 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local replication postgres peer
#host replication postgres 127.0.0.1/32 ident
#host replication postgres ::1/128 ident
Configure the firewall
To configure the port on the firewall, run the following commands:
iptables -I INPUT -p tcp --dport 15000 --syn -j ACCEPT
service iptables save
service iptables restart
root@snwdbsolpeprod01 postt]# service postgresql-9.3 restart
Create a user or role
To create a new user or role in the database, run the following commands:
su – postgres
psql -p 15000
postgres=# CREATE ROLE OCT1 LOGIN
UNENCRYPTED PASSWORD 'test@123'
INHERIT REPLICATION;
Create a tablespace
To create a new tablespace on the database, run the following command:
postgres=# CREATE TABLESPACE OCT1_tablespace
OWNER ilusr
LOCATION '/usrdata/pgsql/data/oct';
Create a database
To create a new database, run the following command:
postgres=# CREATE DATABASE OCT1
WITH ENCODING='UTF8'
OWNER=test
LC_CTYPE='en_US.UTF-8'
CONNECTION LIMIT=-1
TABLESPACE=OCT1_tablespace;
Basic commands
Some basic administration commands include the following ones:
Stop and start PostgreSQL
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data stop
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data start
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data restart
/opt/PostgreSQL/9.3/bin/pg_ctl -D opt/PostgreSQL/9.4/data –m smart stop #wait for complete the transactions
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data –m fast stop #Immediate stop
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data –m immediate stop #Abort the DB
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data –m smart restart
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data –m fast restart
/opt/PostgreSQL/9.3/bin/pg_ctl -D /mnt/postt/data –m immediate restart
Check the PostgreSQL version
postgres=# select version();
Identify the activity on a specific database level
select pid,backend_xid,backend_xmin,query from pg_stat_activity ;
Analyze table status
select relname,last_autoanalyze,last_analyze,n_mod_since_analyze from pg_stat_all_tables;
Find the physical path of a table
postgres=# SELECT pg_relation_filepath('testpitr1');
pg_relation_filepath
----------------------
base/13003/16399
[postgres@postgres221 data]$ ls -l /mnt/postt/data/base/13003/16399
-rw------- 1 postgres postgres 256024576 Feb 21 06:36 /mnt/postt/data/base/13003/16399
Get schema names inside an instance or cluster
select schema_name from information_schema.schemata;
select nspname from pg_catalog.pg_namespace;
post_gre=# \dn
List of schemas
Name | Owner
--------------+----------
kailash_test | postgres
public | postgres
(2 rows)
Get dbnames inside an instance or cluster
template1=# select datname from pg_database;
template1
template0
post_gre
template1=# \l
post_gre | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =Tc/postgres +
| | | | | postgres=CTc/postgres +
| | | | | kailash_s=CTc/postgres
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | |
template1=# select usename from pg_catalog.pg_user;
kailash
kailash_s
postgres
template1=# \du
kailash | | {}
kailash_s | Superuser, Create role, Create DB | {}
postgres | Superuser, Create role, Create DB, Replication | {}
Conclusion
PostgreSQL’s tag line claims that it is “The world’s most advanced open source database.” However, PostgreSQL isn’t just relational, it’s object relational. This distinction gives it some advantage over other open source SQL databases such as MySQL, MariaDB, and Firebird. PostgreSQL is an obvious choice on AWS cloud for migrating in-house RDBMS to an Open Source RDBMS on CLOUD.
In Part 2 of this blog, I cover Postgre backup restore and recovery.
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